2.2 Biological Molecules Flashcards
Describe the structure of a water molecule
- O δ- (attracts more electrons)
- H δ+ (O δ- makes H atoms slightly positive)
- Covalent bond
How is a Hydrogen bond formed in a water molecule?
There is a weak electrical attraction between a hydrogen molecule and an oxygen molecule. This happens because the δ- O bonds are attracted to the δ+ H bonds.
Describe the solvent properties of water
Solvent properties:
•Allows molecules and ions to be transported around living things whilst dissolved in water (as water is polar, the - and + parts are attracted to the + and - parts of the solvent)
•Molecules and ions can be transported around living things whilst dissolved in water
Describe the density+viscosity of water
- Ice is less dense than liquid water as when it goes from 4°C to freezing point the water molecules align themselves in a structure which is less dense (due to water’s polar nature)
- Bodies of water are therefore insulated against cold due to layer of ice on top reducing rate of heat list from rest of pond
- This provides an ideal habitat for living things as is water was less dense, aquatic organisms would find it very difficult to float
Describe the cohesion+surface tension of water
- This makes a drop of water appear spherical because of the H bonding pulling the molecules together
- This explains why water molecules move together
- Allows some insects to walk across water
- Columns of water in plant vascular tissue are pulled up the xylem tissue together from the roots.
Describe the heat and temperature of water
- Water temp is a measure of the kinetic energy of the water molecules
- The amount of Heat Energy required to increase the kinetic energy and temperature is known as the specific heat capacity
- Means that water does not change temp easily
- Living things need a stable temp for enzyme-controlled reactions to take place properly
- Aquatic organisms need a stable environments to live in
What are the 2 different types of glucose?
α-glucose (isomer of glucose)
C6H12O6
•component of glycogen+starch (which act as energy stores) + energy source
β-glucose (isomer of glucose)
C6H12O6
•energy source, component of cellulose (which provides structural support in plant cell walls
What are triglycerides used for?
- energy source + store
- thermal insulator
- buoyancy
- protection
- an example of a macromolecule
How is a triglyceride formed?
- condensation reaction
- H2O molecule is removed
- forms an ester bond.
- left with 3 fatty acid chains joined to glycerol. fatty acids contain carboxyl group. glycerol contains hydroxyl group.
Is a triglyceride saturated or unsaturated?
Unsaturated
What are lipids?
•Biological molecules made of O, C and H -fats, oils, cholesterol, steroids -Animals-fats -plants-oil •soluble in alcohol rather than water •not polar
Describe saturated and unsaturated fats
- Fatty acids can be saturated and unsaturated
- Saturated if the carbon atoms bond to many hydrogen atoms
- Unsaturated if one or more of the fatty acid chains contain C atoms which form a double bond with another C atom
- This means it can’t bond with as many H atoms, forming a “kink” in the chain
Describe glycogen
- energy store in humans
- large polysaccharide molecule
- joined by condensation reactions
- glycosidic bonds between c1-4
- branches between c1-6
Describe cellulose
- found in plants, makes up cell walls
- not starch
- made of β-glucose
- glycosidic bonds c1-4
- not branched straight line not spiralled
- not soluble
- H bonds hold structure in place, stop it spiralling + give strength + stabilise molecules
What are polysaccharides?
Polysaccharides can be made by joining many monosaccharides together.
What is a carbohydrate?
Carbohydrates are organic compounds which comprise of only C, H and O.
•energy source
•energy store
•structural unit
What are monosaccharides
- simplest “simple sugars”
- same no. of C and O atoms
- have the general formula CnH2nOn
- white crystalline solids
- dissolve in water to form sweet tasting solutions
What are disaccharides
Monosaccharides can be joined together to form disaccharides, which dissolve in water and also taste sweet
•condensation reactions
•α1-4 glucose bond formed by hydrolysis
